Electric plug and socket with interlocking terminals



HOP LEE Oct. 10, 1967 ELECTRIC PLUG AND SOCKET WITH INTERLOCKING TERMINALS 2 Sheets-Sheet 1 Filed July 22, 1965 INVENTOB HOPLEE BY 7% d7" TOENEY' HOP LEE Oct. 10, 1967 ELECTRIC PLUG AND SOCKET WITH INTERLOCKING TERMINALS I 2 Sheets-Sheet 2 Filed July 22, 1965 'JNVENTOB Hop 1152 BY M W R2 5 A T TOBNEY United States Fatent fitice 3,346,833 Patented Oct. 10, 1967 3,346,833 ELECTRIC PLUG AND SOCKET WITH INTERLOCKING TERMINALS Hop Lee, 779 Commercial St., San Francisco, Calif. 94108 Filed July 22, 1965, Ser. No. 474,073 4 Claims. (Cl. 339-439) ABSTRACT OF THE DISCLOSURE An electric plug and socket, each comprising an insulating body member with terminals and an insulating cap removably secured to the body. The terminals on the plug are removably receivable in U-shaped terminals in the socket. One of the plug terminals has a lip that engages with a lip on one of the socket terminals for securing the plug to the socket when the plug is rotated through a small arc with respect to the socket.

An object of my invention is to provide an electric plug and socket with interlocking terminals that is an improvement over the electric plug coupling shown in my Patent No. 3,195,100, issued July 13, 1965. In the patent I show a plug and socket with two interconnectible terminals.

My present invention discloses an electric plug and socket with four terminals each. Novel means is provided in the terminals for permitting the interconnecting of the plug terminals with the socket terminals only when the plug and socket are connected with each other in a predetermined manner. This assures that each in-terminal on the plug wil be connected to the same terminal in the socket every time the plug and terminal are connected. In addition the plug and socket may be rotated with respect to each other through a small arc after they are connected and this will lock the plug terminals to the socket terminals and prevent the accidental disengagement of the socket from the plug.

The four terminal plug and socket have been designed primarily to be connected to wiring carrying a threephase current. Three of the terminals are for the curent and the fourth terminal on the plug and socket are to be connected to ground wires. It is possible to have two or more terminals on the plug and socket.

Each of the plug and socket is composed of a base member and a cap. The base member carries the four terminals and the cap covers the wiring connections for the terminals. A two-part casing connects each base member to its cap.

The electric plug and socket is relatively simple in construction and is durable and efiicient for the purpose intended.

Other objects and advantages will appear as the specification continues. The novel features of the invention will be set forth in the appended claims.

Drawings For a better understanding of my invention, reference should be made to the accompanying drawings, forming part of this specification, in which:

FIGURE 1 is a side elevation of the electric plug.

FIGURE 2 is a top plan view of the plug base shown on an enlarged scale and illustrates the cap for the base as being in section and is taken along the line 22 of FIGURE 3.

FIGURE 3 is a vertical section through the plug base and cap and is taken along the line 3-3 of FIGURE 2.

FIGURE 4 is a side elevation of the plug base.

FIGURE 5 is a top plan View of the plug cap and is shown on the same scale as FIGURE 1.

FIGURE 6 is a bottom plan view of the plug cap shown on the same scale as FIGURE 5.

FIGURE 7 is a plan view of a socket base and shows a cap for the base in section and is taken along the line 77 of FIGURE 8.

FIGURE 8 is a vertical section through the socket base and cap and is taken along the line 8-8 of FIGURE 7.

FIGURE 9 is a side elevation of the socket base shown on a smaller scale than FIGURES 7 and 8.

FIGURE 10 is a top plan View of the cap for the socket.

FIGURE 11 is a bottom plan view of cap for the socket.

FIGURE 12 is an isometric view of one of the terminals provided in the electric socket.

FIGURE 13 illustrates the plug and socket interconnected and illustrates how the terminals of the plug contact with the terminals of the socket.

While I have shown only the preferred form of my invention, it should be understood that various changes, or modifications, may be made within the scope of the annexed claims without departing from the spirit thereof.

Detailed description In carrying out my invention, I will first describe the electric plug in detail and then will set forth the construction of the electric socket. The electric plug A is illustrated in FIGURES 1 to 6 inclusive. Both FIGURES 2 and 3 show the electric plug A as comprising a base B made of insulating material and a cap C also being made of insulating material. The plug base B has four terminals preferably made of copper. The terminals D, E and F are identical to each other and a description of one will sufiice for all. The terminal G differs to a slight extent from the other three terminals and this difierence will be set forth after the terminal D is described in detail.

The electric plug terminal D has an upstanding leg 1 that is provided with a laterally extending projection 2 at its outer end. The base of the terminal D is shown at 3 in FIGURE 2 and this base is received in a recess 4 provided in the plug base B, the edge of the recess 4 being similar in shape to the terminal base 3 so that the terminal cannot rotate with respect to the base B. A screw 5 secures the terminal base 3 in the recess 4.

The base 3 has a projection which is curved upwardly to make a half loop shown at 6. This upwardly extending half loop portion of the base 3 constitutes a binding post for receiving the electric wire 7 that extends from a covering sheath 8. The wire 7 is wound around the upwardly curved binding post 6 of the terminal D and then the ends 7a of the wire is bent downwardly so as to be received in a recess 9 provided in the plug base B and disposed adjacent to the binding post 6.

In FIGURE 3, I show a cable H containing four sheathed wires 8. The plug base has a bore 10 for receiving the end of the cable H and the base also has a flange 11 that extends inwardly into the bore 10. This flange has four recesses 12 that receive the sheaths ,8 for the four '2 wires. The top surface 13 of the plug base B has four radially extending grooves 14 that receive the wire sheaths 8 as clearly shown in FIGURE 2. The wires 7 extend from the sheaths 8 and are wrapped around the binding posts 6 of the terminals D to G inclusive. The plug base has four recesses 9 for receiving the ends 7a of the wires.

I show four terminals for the electric plug A. Three of these can be used when the plug is connected to three Wires of a three-phase alternating electric current. The fourth terminal can act as a ground. The four terminals D to G inclusive are spaced equally around the center of the top 13 of the plug base. The terminal G differs. from the other three terminals only in the fact that its laterally extending projection 2 has an inwardly turned lip 2a, see FIGURE 3. The purpose of the lip 2a will be explained herein-after when the electric socket terminals are described. The electric plug does not have to have four wires connected to the four terminals because it is possible for the base to have two or more terminals. One of the terminals will have the inwardly extending lip 2a- The cap C is shown in FIGURES and 6. FIGURE 5 shows the plug cap on a smaller scale than FIGURES 2 and 3..The cap has a closed top 15 that is provided with three spaced apart arcuate openings 16 for receiving the electric terminals D, E and F. The top 15 also has another arcuate opening 17 with an inwardly turned portion 17a for receiving the inwardly turned lip 21: of the terminal G.

FIGURE 6 shows a bottom plan view of the plug cap on the same scale as FIGURE 5. Both FIGURES 3 and 6 show the cap provided with a cylindrical skirt portion 18 that encloses the cylindrical periphery of the plug base. B. The cap has four recesses 19 for receiving the binding posts 6 of the four electrodes. An inner central portion 20 of the cap has partitions29 extending out- Wardly therefrom and these partitions have their outer edges bearing against the top 13 of the plug base so as to form insulating walls between adjacent electric terminals D to G inclusive and to prevent the wires 7 from accidentally contacting with each other. FIGURE 6 shows the plug socket C provided with a key 22 and this key is designed to be received in a key slot 23 in the periphery of the plug base B, see FIGURE 2. It is necessary that the key 22 of the cap be aligned with the slot 23 of the plug base before the cap can he slipped over the base to enclose it in the manner shown in FIG- URE 3.

Both the plug base and cap are secured together by a two-part casing. The casing has a cylindrical part I that encircles the outer periphery of the plug cap as shown in FIGURE 3. The cap has an annular groove 24 disposed adjacent to the top surface 13 of the cap and the rim of the casing I is turned inwardly at 25 so as to fit into the groove. The groove is deep enough to prevent the rim 25 from lying in the plane of the top surface 13 of the plug. The opposite end of the casing part I is threaded at 26.

The other casing part K has a neck portion 27 for receiving the tubular end 28.0f the plug base B. The casing part K has a conical portion 29 that connects with the neck 27 and it has a threaded portion 30 that receives the threaded end 26 of the casing part I. The rim of the threaded portion 30 is bent back on itself to provide a smooth edge and the rim of the neck portion 27 is also bent back upon itself to provide a smooth edge. When the part K is connected to the part I, then the plug base will be permanently secured to the cap C. FIGURE 6 shows the casing part I with three indentations 39 and these are received in three indentations 32 provided in the cylindrical skirt 18 of the cap C. The purpose of the indentations 31 is to prevent the casing part I from rotating with respect to the cap C.

I will now describe the electric socket L in detail. This socket is shown in FIGURES 7 to 12 inclusive. The socket comprises a base M and a cap N, both being 4 made of insulating material. The top 51 of the base is shown in FIGURE 7 and is provided with four recesses 51 for receiving fourterminals indicated generally at,

P, Q, R and S in FIGURE 7. The terminal P is designed to receive the plug terminal G and is shown in FIGURE l2. The terminal P is substantially the same as the other three terminals Q, R and S, except that the terminal P has a lip 52.

A description of the terminal P will sufi'ice for a description of the other three. This terminal has abase 53 that is received in the recess 51 in the top of the socket base M. The base 53 has an inner leg 54 that has an inner curvature 54a lying between the base 53 and the outer end of the leg. In addition the inner leg 54 is concave in cross section and its outer end is curved upwardly as shown at 54b. The terminal is preferably made of copper or some other material that'will conduct electricity. The leg 54 can be flexed slightly when it is brought into contact with the plug terminal G.

The terminal P also has an outer leg 55 and this leg has a lower inclined portion 55a that is integral with the base 53. The leg 55 is curved slightly in the direction of its length and its outer end 55b is curved outwardly The other three socket terminals Q, R and S, are identical to the terminal P except that the inner legs 54 are wider than the inner leg 54 of the terminal P and the lips 52 contact with these legs. Screws 57 are passed through openings in the base 53 and are secured to the socket base M for securing the four socket terminals to the base.

FIGURE 9 shows a socket base N provided with a neck portion 58 and FIGURE 8 shows the neck provided with a bore 59 for receiving a cable T. This cable has four electric wires 60 enclosed in sheaths 61. The end of the cable T abuts an inwardly extending flange 62, see FIGURE 8 and this flange has four recesses 63 for receiving the sheaths 61. The socket base M has four radially extending grooves 64 thatreceive the sheaths 61. The wires 60 extend from the ends of the sheaths 61 and are wrapped around binding posts 65, see FIGURE 12, that are integral with the bases 53 of the socket terminals P to S inclusive. The ends 60a of the wires 60 are bent so as to be received in recesses 66 that are provided in the outer cylindrical surface of the socket base M. In this way the wires 60 are electrically connected to the socket terminals.

The cap M for the socket base N is shown in FIG- URES l0 and 11. The bottom plan view of FIGURE 4 illustrates the socket cap as having four recesses 67, 68, 69 and 70 that are separated from each other by partitions 71 and a central portion 72. FIGURE 8 shows a transverse section through the socket cap N and this is illustrated on a larger scale than that shown in FIGURES 10 and 11. The top of the socket cap is indicated at 73 and the cap has a cylindrical skirt portion 74 whose inner wall is of the-same diameter as the outer cylindrical surface 75 of the socket base M as shown in FIGURE 9.

The four partitions 71 have their outer edges substantially contacting with the top surface 50 of the socket base. This willkeep the four wire sheaths 61 separated from each other so as to prevent any short circuiting of the wires 60. The central portion 72 of the socket cap N cooperates with the partitions 71 in this respect and will cause the wire sheaths 61 to be bent at right angles in order for the sheaths to extend from the four recesses 63 in the flange 62 and enter the four radial grooves 64. It is necessary that the socket cap N be positioned properly with respect to the socket base M and in order to accom- 3 plish this, I provide the cap with a longitudinally extending key 76 that extends inwardly as shown in FIGURE 11. The key is received in a longitudinally extending keyway 77 provided in the cylindrical periphery 75 in the socket base M, see FIGURE 7.

The four recesses 67 to 70 inclusive in the socket cap receive the four electric terminals P to S inclusive. The top 73 of the socket cap has a slot 78, see FIGURE 11, that is provided with an inwardly extending recess 78a. This particular slot with its recess receives the terminal G for the electric plug and as the terminal passes through the slot, it is received between the legs 54 and 55 of the socket terminal P shown at FIGURE 12. A good electric connection between the plug terminal G and the socket terminal P is made because the plug terminal will force the legs 54 and 55 outwardly and there will be a yielding contact between the legs and the terminal. The inwardly turned lip 2a of the plug terminal G will pass through the space 56 provided between the leg 54 and the lip 52 on the socket terminal P.

These socket terminals R and S will be received in the recesses 68, 69 and 70 and the top 73 of the socket cap N will have arcuate slots 79, 80 and 81, for receiving the plug terminals D, E and F, respectively. The plug terminals will extend between the legs 54 and 55 of each of the socket terminals Q, R and S, for making a good electrical contact.

Before the socket is connected to the plug, the base M of the socket is permanently connected to the cap N. This is accomplished by a metal casing that has a cylindrical part U that encircles the cylindrical skirt 74 of the cap N. The socket cap N has an annular groove 82 that receives an inwardly extending flange 83 of the cylindrical casing part U. The other end of the casing part U is threaded at 84 for receiving the threadai portion 85 of the other casing part V that encloses the socket base M.

The casing part V has a neck portion 86, see FIGURE 8, for receiving the neck portion 58 of the socket base. The outer end of the casing neck 86 is turned back on itself at 86a to provide a smooth edge. In like manner the edge of the casing part B that is disposed adjacent to the threaded portion 85 is turned back on itself at 87 for providing a smooth edge. The cylindrical skirt 74 of the socket N has spaced apart indentations 88, see FIG- URE 11, for receiving inwardly pressed portions 89 of the casing part U. These indentations are made adjacent to the outer edge of the cylindrical skirt 74 and are for the purpose of preventing relative rotation between the casing part U and the socket cap N.

In FIGURE 13, I show the electric plug connected to the electric socket. This figure is partly shown in section so as to illustrate how the plug terminal G is received in the socket terminal P. Also the plug terminal E is shown being received in the socket terminal S. In order to prevent the plug from becoming accidentally disconnected from the socket, the plug is rotated through a slight arc with respect to the socket after the plug terminals have been received in the socket terminals. This will cause the lateral projection 2 on all four of the plug terminals, see FIGURES 3 and 4, to be moved so that the lower shoulders 212 will extend under the lips 52 of the socket terminals. It is now impossible to pull the plug free from the socket until the socket and plug are rotated with respect to each other back into their former position.

To accomplish this, the operator first rotates the plug with respect to the socket in a direction for freeing the lower shoulders 2b from engagement with the lips 52 of the socket terminals. When this is done, the plug can be moved away from the socket in a direction paralleling the axis of the plug and socket and this will free the plug terminals from the socket terminals.

I claim:

1. In a device of the type described; a socket comprising:

(a) a body member made of insulating material and having an end and a bore extending longitudinally through said body for receiving electric wires;

(b) a plurality of two-pronged electrodes secured to the end of said body; all of said electrodes having an integral lip at the outer end "of one prong in each electrode that extends at an angle toward the other associate prong; all but one of said lips being with such prong; said one lip being spaced from the adjacent side of its associate prong;

(c) an insulating cap for said body and having slots registering with the outer ends of the prongs of said electrodes; one of said slots having a recess extend ing at an angle to the slot for registering with the lip of said electrode that is spaced from the adjacent side of its other prong; and

(d) a two-part casing for securing said cap to said body.

2. The combination as set forth in claim 1: and in which (a) said two-part casing having mating threaded ends for removably securing the two parts of the casing together;

(b) one casing part being secured to said body; and

(c) the other casing part secured to said cap.

3. The combination as set forth in claim 1: and in which (a) said cap has a cavity for receiving said electrodes and has an inwardly-extending and axially aligned projection with outwardly extending partitions that divide the cavity into a number of electrode-receiving compartments equal in number to the number of electrodes;

(b) said partitions electrically isolating the electrodes from each other.

4. A device of the type described comprising:

(a) a plug composed of (b) a body having an end;

(c) a plurality of electrodes secured to the end of said body;

(d) each of said electrodes having an outwardly-extending terminal, the terminals lying equidistant from the center of said body and being spaced from each other; all of said terminals having laterally-extending portions, each providing a shoulder at their inner edge;

(e) one of said terminals having an integral lip at the outer end of said laterally-extending portion that extends substantially in a radial direction with respect to the axis of said body;

(f) an insulating cap for said body and having slots for permitting said terminals to extend therethrough; one of said slots having a recess extending at an angle to the slot for receiving the lip on one of said terminals; and

(g) a two-part casing for securing said cap to said body;

(h) a socket composed of (i) a second body member made of insulating material and having an end and a bore extending longitudinally through said body for receiving electric wires;

(j) a plurality of two-pronged electrodes secured to the end of said second body; all of said two-pronged electrodes having an integral lip at the outer end of one prong in each electrode that extends at an angle toward the other associate prong; all but one of said lips being with such prong; said one lip being spaced from the adjacent side of its associate prong;

(k) a second insulating cap for said second body and having slots registering with the outer ends of the prongs; one of said slots having a recess extending at an angle to the slot for registering with the lip of said second electrode that is spaced from the adjacent side of its associate prong;

(l) a two-part casing for securing said second cap to said second body;

7 (m) the terminals of said plug body being adapted to enter the slots in said second cap and move between the two prongs in each socket electrode, the lip on one of said terminals first being aligned with the recess in said second cap that extends at an angle to the slot in said second cap;

(n) the laterally-extending portions on said plug terminals having their shoulders pass beyond the lips on said socket terminals;

(o) whereby said plug may be rotated with respect to said socket through an angle for moving said shoulders on said laterally-extending portions under said lips of said socket electrodes for preventing accidental disconnection of said plug from said socket.

References Cited UNITED STATES PATENTS Anderson 339139 Benander 339-196 Hubbell et a1 339-91 Huhbell 339-14 X 

1. IN A DEVICE OF THE TYPE DESCRIBED; A SOCKET COMPRISING: (A) A BODY MEMBER MADE OF INSULATING MATERIAL AND HAVING AN END AND A BORE EXTENDING LONGITUDINALLY THROUGH SAID BODY FOR RECEIVING ELECTRIC WIRES; (B) A PLURALITY OF TWO-PRONGED ELECTRODES SECURED TO THE END OF SAID BODY; ALL OF SAID ELECTRODES HAVING AN INTEGRAL LIP AT THE OUTER END OF ONE PRONG IN EACH ELECTRODE THAT EXTENDS AT AN ANGLE TOWARD THE OTHER ASSOCIATE PRONG; ALL BUT ONE OF SAID LIPS BEING WITH SUCH PRONG; SAID ONE LIP BEING SPACED FROM THE ADJACENT SIDE OF ITS ASSOCIATE PRONG; 